Augmenting volume management of information storage devices to handle direct access to storage devices

Apparatus for managing volume access requests and device access requests to information storage devices, said apparatus comprising:

• a volume data storage element for storing characteristics of each storage device as volume data for each storage device, said volume data including characteristics indicating the open status of the storage device;
• a volume access processor responsive to a request to access a volume in a first storage device, said volume access processor for testing characteristics from volume data for the first storage device to determine the open status of the first storage device;
• said volume access processor processing the volume access request, granting the request based on the open status and updating the characteristics in the volume data so that said characteristics indicate the updated open status of the first storage device;
• a device access processor responsive to a request to access the first storage device, said device access processor testing characteristics from the volume data for the first storage device to determine the open status of the first storage device;
• said device access processor processing the device access request, granting the request based on the open status and updating the characteristics in the volume data so that said characteristics indicate the updated open status of the first storage device, whereby said volume access processor and said device access processor are operated in parallel and each access the first storage device and manage conflicts for exclusive access.

A method for managing storage devices in a computing system comprising the steps of:

• Storing a characteristic list for each storage device, the characteristic list including an open count indicating the number of current open requests to each device and including an exclusive flag indicating whether or not the device has been opened exclusively by a request;
• in response to an open volume request, detecting, by an open volume operative system, from the exclusive flag in the requested device characteristic list whether the requested device is already exclusively open and detecting from the open volume request whether a request for a storage device is an exclusive open request and testing the open count in the requested device characteristic list to detect if the requested device is already open whereby the availability of the storage device is determined;
• and
• in response to an open device request, detecting, by an open device operative system, from the exclusive flag in the requested device characteristic list whether the requested device is already exclusively open, and detecting from the open device request whether a request for a storage device is an exclusive open request and testing the open count in the requested device characteristic list to detect if the requested device is already open whereby the availability of the storage device is determined;
• wherein the open volume operative system and the open device operative system are operated in parallel without conflict.

A computer program storage medium readable by a computing system and encoding a program of instruction for executing a computer process in response to an open volume request or an open device request by a user of the computing system including an open volume operative system and open device operative system which are operated in parallel, said computer process comprising the steps of:

• instructing said computing system to store characteristic list for an information storage device, the characteristic list including a first characteristic indicating whether or not the storage device is currently open for access and a second characteristic indicating whether or not the storage device is currently open for exclusive access;
• instructing an open volume operative system, in response to said open volume request, to test the first characteristic to determine whether the requested device is already open,
• to test the second characteristic to determine whether the requested device is already exclusively open,
• to detect whether said open volume request is an exclusive open volume request,
• to grant said open volume request and setting said first characteristic to open if the request is not an exclusive open request, otherwise return a busy code to the computing system;
• instructing an open device operative system, in response to said open device request, to test the first characteristic to determine whether the requested device is already open,
• to test the second characteristic to determine whether the requested device is already exclusively open,
• to detect whether said open device request is an exclusive open device request;
• to grant said open device request and setting said first characteristic to open if the request is not an exclusive open request, otherwise return a busy code to the computing system.